Resolution in crosshole seismic tomography has been studied in this paper by means of ray density, ray orthogonality and point-spread function. Numerical experiments indicate that the resolution is better in the vertical direction than in the horizontal, and the high velocity anomalous body is different from the low velocity anomalous body in resolution and shapes of tomography. For the high velocity anomalous body, the spatial resolution of the waveform velocity tomogram in horizontal is about 1/2 of the wavelength, and that in vertical about 3/10 of the wavelength. For the low velocity anomalous body, the spatial resolution of the waveform velocity tomogram in horizontal is about 2/5 of the wavelength, and that in vertical about 1/5 of the wavelength. The spatial resolution of the traveltime velocity tomogram in horizontal is about three tomographic elements width, and that in horizontal about two tomographic elements width. When the ratio between the borehole depth and well offset is equal to 2.0, the spatial resolution of the velocity tomogram is the best.
[1] 曹俊兴,严忠琼. 地震波跨孔旅行时层析成像分辨率的估计[J].成都理工学院学报,1995,22(4).
[2] 陈国金. 井间观测系统的讨论[J].石油物探,1996,35(3).
[3] 杨文采,杜剑渊. 煤矿陷落柱地震层析成像试验[J].物探与化探,1992,16(3).
[4] 赵永贵,王超凡,陈燕民,等. 地震CT在寻找隐伏铜镍矿中的应用[J].地球物理学报,1996,39(2).
[5] Backus G,Gilbert F. The resolving power of gross earth data[J].Geophys. J. R. Astr. Soc.,1968,16(1):169-205.
[6] Humphreys J T,Clayton R W.Adaption of back projection tomo-graphy to seismic traveltime problems[J].J.G.R.,1988,93:1073-1085.
[7] Rector III J W,Washbourne J K. Characterization of resolutionand uniqueness in crosswell direct-arrival traveltime tomographyusing the Fourier Projection slice theorem[J].Geophysics,1994,59(11):1642-1649.
[8] Schuster G T.Resolution limits for crosswell migration and tra-veltime tomography Geophys[J].J.Int.,1996,127(2):427-440.
[9] Williamson P R,Worthington M N. A guide to the limits of re-solution imposed by scattering in ray tomography[J].Geophy-sics,1991,56(2):202-207.
[10] Williamson P R,Worthington M H. Resolution limits in raytomography due to wave behavior: Numerical experiments[J].Geophysics,1993,58(5):727-735.
[11] 冯锐.西北地区的基地速度图像[J].地球物理学报,1991,34(4).
[12] Wu R S, Toksoz M N. Diffraction tomography and multisourceholography applied to seismic imaging[J].Geophysics,1987,52(1):11-25.